600 carb issue

could the float have a hole in it ?
shake it to see if you can hear fuel in it.

Do you know what your fuel pressure is?

I removed both floats and check for leaks. Both passed and no damage noted on eather one of them. I thought that the secondary float may have been hitting the blank off plate with a secondary gasket installed, it wasn't on when I removed the bowl but showed it on the rebuild kit diagram. I removed it and there was no difference. I haven't gotten a pressure gauge yet though my vacuum gauge is suppose to be able to read the fuel pressure so I may try that next. The enitial vac was reading real low so I suspected a vac leak but after checking and spraying everything there were no leaks. After retiming and the second install of the carb I was right on the numbers, 18in. at the manifold. I thought about the fuel pressure but couldn't figure why one bowl was fluiding and the other lean. A new Fuel filter was installed as well. As soon as I made any float adjustment is when everything went south. I'm thinking the power valve is defective in the kit and ordered another for delivery today along with a new set of blue gaskets, the first set only lasts 3 times. It's like lots of fuel is getting to the secondary bowl but not the primary, checked the carb filter as well. Darn...

Steve in VA

are you sure the needle and seat are correct of the flooding bowl? just a hunch

> When I go to adjust the float level (the engine is off) gas is
> spraying out of the external adjusting nuts as soon as I loosen
> the lock screw. I can't believe your suppose to do this with the
> engine running

This is not necessarily abnormal. You need to just barely
loosen the lock screw then back both the adjustment and the lock
off together. In practice, I back the lock screw off until gas
sprays out then I tighten it back up enough to keep gas from
spraying out, then I move both the nut and screw in unison.
Willys even makes a little tool for this.

> adjusted the floats to "inverted level" then reinstalled the carb.
> On startup the motor sounded pritty good, idled fine and after a
> little smoke the exhaust sounded good. I cracked the site plugs
> and found the same results, fuel above the secondary site hole and
> below the primary float hole.

That may be due to the fact the carb is not level as installed.
Most street intake manifolds have a canted carb pad because the
cars they were designed for mount the engine nose high. The
cant levels the carb. The Pantera, however, mounts the engine
level so the carb ends up nose down. That causes the fuel to
drain away from the sight hole (and jets) on the primary side
and towards the sight hole on secondary side. You may have to
lower the secondary float and raise the primary slightly. After
you've got it where you think it is right, do a braking test
from 30 mph or so with the engine in neutral. If it dies, the
primary float is still a bit low (fuel is sloshing away). Don't
raise the float too high or you will run rich across the board.

> I adjusted the levels 1/4 turn and the Pan won't hold an idle,
> falls right off like it's starving for fuel or flooding. If I
> rev up to 2000 it will run but sounds like it's got a slight
> miss.

It is likely too lean on the idle circuit. I'm assuming this
is on an engine that is fully warmed up (and therefore not due
to the choke going open too soon). The higher the level of
fuel in the primary float, the richer the idle circuit will
be. If it's too low, the idle leans out and may not hold an
idle until you start pulling in additional fuel from the main
jets. Even then it may be lean and pop and miss. You must get
the float levels right before doing any other tuning.

> but after runnning the adjuster all the way down on the secondary
> float gas was still spilling out of the sight hole.

That is not normal. Maybe the needle valve is bad causing too
much gas to get into the float bowl. Another possibility is
the fuel is boiling (needs an insulator gasket or spacer between
the intake and carb).

Dan Jones

with the sec bowl removed, blow in the fuel inlet and lift the float and see if it shuts off the needle.
maybe the needle is damaged.

I did the pressure test on the floats v8 operating them manualy and they shut off the flow of air. I had also replaced both needle valves at the floats first time around and still have the issue of flooding the secondary bowl. I'm going to do a fuel pump pressure test this weekend and see what the pressure is and figure out a volume test on it as well. The flooding secondary occurs quickly Dan, the carb is hot enough to disingauge the choke but not hot enough to start a fire (I hope)when I shut it down for some thinking time. Like I said above, it's like the fuel is by-passing the primary bowl and flooding the secondary. I don't see how a pump will increase pressure over time but who knows, I've seen stranger things...

Thanks all,
Steve

Here's an update from this weekends testing.
I did a pressure test on the fuel pump. Turns out I'm at 8.5 lbs right off the bat while cranking for 5 seconds. Since this was a dead head to the gauge and not to the carberator I figure this is what pressure I'm putting on the float needle and seat when closed. As I'm staring at the gauge contimplating this the gauge continues to rise above 10 lbs! I figure this is do to the static pressure build-up on the pump diaphram. I would prefer to stay with a manual pump rather than electric however it seems that no manufacture I have found will eather specify their discharge pressure or even print the specs for there pumps. The good news is the solution to a number of issues are pointing to replacing the pump.

Steve in VA

Pressures are too high.

Install a pressure regulator.

Larry

Although it is pricey, the best mechanical fuel pump attainable for the 351C is found here. The best is always pricey. This is a true race quality pump. Not the "hot rod" crap sold by Holley and others.

cowboy from hell

Update on my carb issues.
I've replaced the fuel pump and tested it to provide 5.3 lbs at the carb. Adjusted the floats at first to just at the site holes, fired her up and pritty much the same results, will start right up then about 10 seconds falls off and won't idle unless I give it a shot of gas. I adjusted the float on the primary side a little richer and still the same thing but I started to notice black smoke from the exhaust. The choke opens rather quickly so I don't think it's an issue with the choke. Once the car warms up the idle is ok but I notice a slightly rough idle and it continues with some throttle. I adjusted the timing to 20d BTDC with no change. The Vacuum gage reads about 16hg fairly steady with little change. I'm just about ready to go buy a 670 Holley but would like to see if there is anything else I might have missed. I did check the cap and rotor and changed out the plugs prior to this and all looked real good. any other input??

Thanks for the help guys,
Steve in VA